Spring源码-09-Bean工厂之getBean方法
Bean实例
一 getBean方法
// AbstractBeanFactory.java
@Override
public Object getBean(String name) throws BeansException {
return this.doGetBean(name, null, null, false);
}
@Override
public <T> T getBean(String name, Class<T> requiredType) throws BeansException {
return doGetBean(name, requiredType, null, false);
}
@Override
public Object getBean(String name, Object... args) throws BeansException {
return doGetBean(name, null, args, false);
}
二 doGetBean方法
// AbstradtBeanFactory.java
protected <T> T doGetBean(
String name, @Nullable Class<T> requiredType, @Nullable Object[] args, boolean typeCheckOnly)
throws BeansException {
/**
* beanName
* - &开头的name标识FactoryBean 转换成beanName
* - 别名转换成beanName
*/
String beanName = transformedBeanName(name);
Object beanInstance;
// Eagerly check singleton cache for manually registered singletons.
/**
* 第一次调用 getSingleton方法多个重载版本
* 检查单例池是否缓存了Bean
* - 可能通过手动方式先注册了单例Bean
* 尝试性获取单例Bean
* - 要获取的目标Bean对象可能是单例
* - 已经缓存过一级缓存就不需要再创建了 直接获取到
* - 一级缓存还没有说明需要创建
* - 也可能是原型的 原型Bean在一级缓存中肯定获取不到
* 根据获取结果决定是否要执行Bean创建流程 创建的时候再区分是单例还是原型
* - 将单例Bean缓存
* - 原型Bean每次请求创建一次
*/
Object sharedInstance = super.getSingleton(beanName);
if (sharedInstance != null && args == null) { // Bean已经实例化过 但是不一定初始化过
if (logger.isTraceEnabled()) {
if (isSingletonCurrentlyInCreation(beanName)) {
logger.trace("Returning eagerly cached instance of singleton bean '" + beanName +
"' that is not fully initialized yet - a consequence of a circular reference");
}
else {
logger.trace("Returning cached instance of singleton bean '" + beanName + "'");
}
}
/**
* Bean实例
* - 普通Bean对象 sharedInstance就是Bean实例
* - FactoryBean
* - name标识需要获取的就是FactoryBean
* - 需要获取的是普通Bean 通过FactoryBean的getObject创建Bean实例
*/
beanInstance = getObjectForBeanInstance(sharedInstance, name, beanName, null);
}
else {
// Fail if we're already creating this bean instance:
// We're assumably within a circular reference.
if (this.isPrototypeCurrentlyInCreation(beanName)) {
throw new BeanCurrentlyInCreationException(beanName);
}
// Check if bean definition exists in this factory.
BeanFactory parentBeanFactory = getParentBeanFactory();
if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {
// Not found -> check parent.
String nameToLookup = originalBeanName(name);
if (parentBeanFactory instanceof AbstractBeanFactory abf) {
return abf.doGetBean(nameToLookup, requiredType, args, typeCheckOnly);
}
else if (args != null) {
// Delegation to parent with explicit args.
return (T) parentBeanFactory.getBean(nameToLookup, args);
}
else if (requiredType != null) {
// No args -> delegate to standard getBean method.
return parentBeanFactory.getBean(nameToLookup, requiredType);
}
else {
return (T) parentBeanFactory.getBean(nameToLookup);
}
}
if (!typeCheckOnly) {
this.markBeanAsCreated(beanName); // 标识Bean开始创建
}
StartupStep beanCreation = this.applicationStartup.start("spring.beans.instantiate")
.tag("beanName", name);
try {
if (requiredType != null) {
beanCreation.tag("beanType", requiredType::toString);
}
RootBeanDefinition mbd = this.getMergedLocalBeanDefinition(beanName); // BeanDefinition可能有父类 合并父类属性
checkMergedBeanDefinition(mbd, beanName, args); // 确保BeanDefinition的Class不是抽象的
// Guarantee initialization of beans that the current bean depends on.
String[] dependsOn = mbd.getDependsOn(); // 依赖的Bean先实例化
if (dependsOn != null) {
for (String dep : dependsOn) {
if (isDependent(beanName, dep)) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Circular depends-on relationship between '" + beanName + "' and '" + dep + "'");
}
registerDependentBean(dep, beanName);
try {
this.getBean(dep); // 被依赖的Bean先实例化 递归调用
}
catch (NoSuchBeanDefinitionException ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"'" + beanName + "' depends on missing bean '" + dep + "'", ex);
}
}
}
// Create bean instance.
/**
* 真正开始创建Bean
* - 单例Bean创建完成后要缓存起来
* - 原型Bean创建完成后不需要缓存
*/
if (mbd.isSingleton()) { // 单例Bean
/**
* 第二次调用 getSingleton方法多个重载版本
* 还没获取到缓存的单例Bean
* - 先回调执行Bean的创建
* - 负责将创建好的单例Bean缓存
*
* getSingleton获取单例Bean对象
* - singletonObjects 取一级缓存
* - 没有一级缓存 Bean正在创建中
* - createBean方法创建Bean对象
* - 代理Bean对象
* - 常规Bean对象
* - createBeanInstance方法 Bean的实例化
* - 工厂方法
* - 自动注册参数 有参构造方法
* - 默认构造器 无参构造方法
* - addSingletonFactory方法 将Bean的objectFactory放到三级缓存
* - populate方法 Bean属性填充
* - initializeBean方法 Bean初始化
* - Aware接口回调
* - BeanNameAware 回调setBeanName方法
* - BeanClassLoaderAware 回调setBeanClassLoader方法
* - BeanFactoryAware 回调setBeanFactor方法
* - 回调BeanPostProcessor后置处理器postProcessBeforeInitialization方法
* - 回调InitializingBean的afterPropertiesSet方法
* - 执行init-method方法
* - 回调BeanPostProcessor后置处理器postProcessAfterInitialization方法
* - addSingleton方法缓存单例Bean对象
* - 添加一级缓存
* - 移除二级缓存
* - 移除三级缓存
*/
sharedInstance = getSingleton(beanName, () -> {
try {
return createBean(beanName, mbd, args); // Bean实例化 Bean初始化填充属性 Bean后置处理器
}
catch (BeansException ex) {
// Explicitly remove instance from singleton cache: It might have been put there
// eagerly by the creation process, to allow for circular reference resolution.
// Also remove any beans that received a temporary reference to the bean.
destroySingleton(beanName);
throw ex;
}
});
beanInstance = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
}
else if (mbd.isPrototype()) { // 原型Bean
// It's a prototype -> create a new instance.
Object prototypeInstance = null;
try {
beforePrototypeCreation(beanName);
prototypeInstance = this.createBean(beanName, mbd, args); // 创建Bean
}
finally {
afterPrototypeCreation(beanName);
}
beanInstance = getObjectForBeanInstance(prototypeInstance, name, beanName, mbd);
}
else {
String scopeName = mbd.getScope();
if (!StringUtils.hasLength(scopeName)) {
throw new IllegalStateException("No scope name defined for bean '" + beanName + "'");
}
Scope scope = this.scopes.get(scopeName);
if (scope == null) {
throw new IllegalStateException("No Scope registered for scope name '" + scopeName + "'");
}
try {
Object scopedInstance = scope.get(beanName, () -> {
beforePrototypeCreation(beanName);
try {
return createBean(beanName, mbd, args);
}
finally {
afterPrototypeCreation(beanName);
}
});
beanInstance = getObjectForBeanInstance(scopedInstance, name, beanName, mbd);
}
catch (IllegalStateException ex) {
throw new ScopeNotActiveException(beanName, scopeName, ex);
}
}
}
catch (BeansException ex) {
beanCreation.tag("exception", ex.getClass().toString());
beanCreation.tag("message", String.valueOf(ex.getMessage()));
cleanupAfterBeanCreationFailure(beanName);
throw ex;
}
finally {
beanCreation.end();
}
}
return adaptBeanInstance(name, beanInstance, requiredType);
}
1 getSingleton
// DefaultSingletonBeanRegistry.java
/**
* 获取单例Bean对象
* - 取一级缓存
* - 没有一级缓存 Bean正在创建中
* - createBean方法创建Bean对象
* - 代理Bean对象
* - 常规Bean对象
* - createBeanInstance方法 Bean的实例化
* - addSingletonFactory方法 将Bean的objectFactory放到三级缓存
* - populate方法 Bean属性填充
* - initializeBean方法 Bean初始化
* - addSingleton方法缓存单例Bean对象
* - 添加一级缓存
* - 移除二级缓存
* - 移除三级缓存
*/
public Object getSingleton(String beanName, ObjectFactory<?> singletonFactory) { // 传进来的lambda是函数式接口的实现 用于回调执行 创建Bean实例
Assert.notNull(beanName, "Bean name must not be null");
synchronized (this.singletonObjects) {
Object singletonObject = this.singletonObjects.get(beanName); // 一级缓存
if (singletonObject == null) {
if (this.singletonsCurrentlyInDestruction) {
throw new BeanCreationNotAllowedException(beanName,
"Singleton bean creation not allowed while singletons of this factory are in destruction " +
"(Do not request a bean from a BeanFactory in a destroy method implementation!)");
}
if (logger.isDebugEnabled()) {
logger.debug("Creating shared instance of singleton bean '" + beanName + "'");
}
this.beforeSingletonCreation(beanName); // 缓存起来标识正在创建Bean对象
boolean newSingleton = false;
boolean recordSuppressedExceptions = (this.suppressedExceptions == null);
if (recordSuppressedExceptions) {
this.suppressedExceptions = new LinkedHashSet<>();
}
try {
singletonObject = singletonFactory.getObject(); // 回调lambda表达式 触发createBean(...)执行
newSingleton = true;
}
catch (IllegalStateException ex) {
// Has the singleton object implicitly appeared in the meantime ->
// if yes, proceed with it since the exception indicates that state.
singletonObject = this.singletonObjects.get(beanName);
if (singletonObject == null) {
throw ex;
}
}
catch (BeanCreationException ex) {
if (recordSuppressedExceptions) {
for (Exception suppressedException : this.suppressedExceptions) {
ex.addRelatedCause(suppressedException);
}
}
throw ex;
}
finally {
if (recordSuppressedExceptions) {
this.suppressedExceptions = null;
}
afterSingletonCreation(beanName);
}
/**
* 回调执行完成了单例Bean的创建
* 负责将单例Bean缓存
* - 添加一级缓存
* - 删除二级缓存
* - 删除三级缓存
*/
if (newSingleton) {
this.addSingleton(beanName, singletonObject); // 单例Bean缓存起来
}
}
return singletonObject;
}
}
2 createBean
// AbstractAutowireCapableBeanFactory.java
/**
* Bean对象创建
* - 代理Bean对象
* - 常规Bean对象
* - createBeanInstance方法 Bean的实例化
* - 工厂方法
* - 自动注册参数 有参构造方法
* - 默认构造器 无参构造方法
* - addSingletonFactory方法 将Bean的objectFactory放到三级缓存
* - populate方法 Bean属性填充
* - initializeBean方法 Bean初始化
* - Aware接口回调
* - BeanNameAware 回调setBeanName方法
* - BeanClassLoaderAware 回调setBeanClassLoader方法
* - BeanFactoryAware 回调setBeanFactor方法
* - 回调BeanPostProcessor后置处理器postProcessBeforeInitialization方法
* - 回调InitializingBean的afterPropertiesSet方法
* - 执行init-method方法
* - 回调BeanPostProcessor后置处理器postProcessAfterInitialization方法
*/
@Override
protected Object createBean(String beanName, RootBeanDefinition mbd, @Nullable Object[] args)
throws BeanCreationException {
if (logger.isTraceEnabled()) {
logger.trace("Creating instance of bean '" + beanName + "'");
}
RootBeanDefinition mbdToUse = mbd;
// Make sure bean class is actually resolved at this point, and
// clone the bean definition in case of a dynamically resolved Class
// which cannot be stored in the shared merged bean definition.
Class<?> resolvedClass = resolveBeanClass(mbd, beanName);
if (resolvedClass != null && !mbd.hasBeanClass() && mbd.getBeanClassName() != null) {
mbdToUse = new RootBeanDefinition(mbd);
mbdToUse.setBeanClass(resolvedClass);
}
// Prepare method overrides.
try {
/**
* override method
* - loop-method
* - replace-method
*/
mbdToUse.prepareMethodOverrides();
}
catch (BeanDefinitionValidationException ex) {
throw new BeanDefinitionStoreException(mbdToUse.getResourceDescription(),
beanName, "Validation of method overrides failed", ex);
}
try {
// Give BeanPostProcessors a chance to return a proxy instead of the target bean instance.
/**
* Spring常规单例Bean实例化前的预处理时机
* - 如果有InstantiationAwareBeanPostProcessor类型的后置处理器为Bean创建出来了代理对象
* - 就不需要Spring负责后续的生命周期了 将Spring创建Bean对象的流程短路终止掉
* - 为Bean代理对象执行Bean后置处理器回调
* - 不创建代理对象就由Spring托管常规Bean的创建流程
*/
Object bean = resolveBeforeInstantiation(beanName, mbdToUse);
if (bean != null) {
return bean;
}
}
catch (Throwable ex) {
throw new BeanCreationException(mbdToUse.getResourceDescription(), beanName,
"BeanPostProcessor before instantiation of bean failed", ex);
}
try {
/**
* 常规Bean的创建
* - createBeanInstance方法 Bean的实例化
* - 工厂方法
* - 自动注册参数 有参构造方法
* - 默认构造器 无参构造方法
* - addSingletonFactory方法 将Bean的objectFactory放到三级缓存
* - populate方法 Bean属性填充
* - initializeBean方法 Bean初始化
* - Aware接口回调
* - BeanNameAware 回调setBeanName方法
* - BeanClassLoaderAware 回调setBeanClassLoader方法
* - BeanFactoryAware 回调setBeanFactor方法
* - 回调BeanPostProcessor后置处理器postProcessBeforeInitialization方法
* - 回调InitializingBean的afterPropertiesSet方法
* - 执行init-method方法
* - 回调BeanPostProcessor后置处理器postProcessAfterInitialization方法
*/
Object beanInstance = this.doCreateBean(beanName, mbdToUse, args);
if (logger.isTraceEnabled()) {
logger.trace("Finished creating instance of bean '" + beanName + "'");
}
return beanInstance;
}
catch (BeanCreationException | ImplicitlyAppearedSingletonException ex) {
// A previously detected exception with proper bean creation context already,
// or illegal singleton state to be communicated up to DefaultSingletonBeanRegistry.
throw ex;
}
catch (Throwable ex) {
throw new BeanCreationException(
mbdToUse.getResourceDescription(), beanName, "Unexpected exception during bean creation", ex);
}
}
// AbstractAutowireCapableBeanFactory.java
/**
* 常规Bean的创建
* - createBeanInstance方法 Bean的实例化
* - 工厂方法
* - 自动注册参数 有参构造方法
* - 默认构造器 无参构造方法
* - addSingletonFactory方法 将Bean的objectFactory放到三级缓存
* - populate方法 Bean属性填充
* - initializeBean方法 Bean初始化
* - Aware接口回调
* - BeanNameAware 回调setBeanName方法
* - BeanClassLoaderAware 回调setBeanClassLoader方法
* - BeanFactoryAware 回调setBeanFactor方法
* - 回调BeanPostProcessor后置处理器postProcessBeforeInitialization方法
* - 回调InitializingBean的afterPropertiesSet方法
* - 执行init-method方法
* - 回调BeanPostProcessor后置处理器postProcessAfterInitialization方法
*/
protected Object doCreateBean(String beanName, RootBeanDefinition mbd, @Nullable Object[] args)
throws BeanCreationException {
// Instantiate the bean.
BeanWrapper instanceWrapper = null;
if (mbd.isSingleton()) {
instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);
}
if (instanceWrapper == null) {
/**
* Bean实例化
* - 工厂方法
* - 提供了自动注入的参数 有参构造方法
* - 默认构造器 无参构造方法
*/
instanceWrapper = this.createBeanInstance(beanName, mbd, args);
}
// Bean实例已经创建好了
Object bean = instanceWrapper.getWrappedInstance();
Class<?> beanType = instanceWrapper.getWrappedClass();
if (beanType != NullBean.class) {
mbd.resolvedTargetType = beanType;
}
// Allow post-processors to modify the merged bean definition.
synchronized (mbd.postProcessingLock) {
if (!mbd.postProcessed) {
try {
/**
* @Autowired
* @Value
*/
applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
}
catch (Throwable ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Post-processing of merged bean definition failed", ex);
}
mbd.markAsPostProcessed();
}
}
// Eagerly cache singletons to be able to resolve circular references
// even when triggered by lifecycle interfaces like BeanFactoryAware.
/**
* 解决循环依赖 返回值标识存在循环依赖
* - 单例
* - 允许循环依赖
* - 正处在循环依赖的创建流程中
*/
boolean earlySingletonExposure = (mbd.isSingleton() && this.allowCircularReferences &&
isSingletonCurrentlyInCreation(beanName));
if (earlySingletonExposure) {
if (logger.isTraceEnabled()) {
logger.trace("Eagerly caching bean '" + beanName +
"' to allow for resolving potential circular references");
}
/**
* 将创建Bean的objectFactory缓存到三级缓存中
*/
addSingletonFactory(beanName, () -> getEarlyBeanReference(beanName, mbd, bean));
}
// Initialize the bean instance.
Object exposedObject = bean;
try {
/**
* Bean属性填充
* - 可能依赖其他的Bean
*/
populateBean(beanName, mbd, instanceWrapper);
/**
* Bean初始化
* - Aware接口回调
* - BeanNameAware 回调setBeanName方法
* - BeanClassLoaderAware 回调setBeanClassLoader方法
* - BeanFactoryAware 回调setBeanFactor方法
* - 回调BeanPostProcessor后置处理器postProcessBeforeInitialization方法
* - 回调InitializingBean的afterPropertiesSet方法
* - 执行init-method方法
* - 回调BeanPostProcessor后置处理器postProcessAfterInitialization方法
*/
exposedObject = this.initializeBean(beanName, exposedObject, mbd);
}
catch (Throwable ex) {
if (ex instanceof BeanCreationException bce && beanName.equals(bce.getBeanName())) {
throw bce;
}
else {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, ex.getMessage(), ex);
}
}
if (earlySingletonExposure) { // 存在循环依赖 已经将创建Bean的objectFactory放在了三级缓存了
Object earlySingletonReference = getSingleton(beanName, false); // 通过三级缓存的objectFactory的getObject方法获取了实例对象
if (earlySingletonReference != null) {
if (exposedObject == bean) {
exposedObject = earlySingletonReference;
}
else if (!this.allowRawInjectionDespiteWrapping && hasDependentBean(beanName)) {
String[] dependentBeans = getDependentBeans(beanName);
Set<String> actualDependentBeans = new LinkedHashSet<>(dependentBeans.length);
for (String dependentBean : dependentBeans) {
if (!removeSingletonIfCreatedForTypeCheckOnly(dependentBean)) {
actualDependentBeans.add(dependentBean);
}
}
if (!actualDependentBeans.isEmpty()) {
throw new BeanCurrentlyInCreationException(beanName,
"Bean with name '" + beanName + "' has been injected into other beans [" +
StringUtils.collectionToCommaDelimitedString(actualDependentBeans) +
"] in its raw version as part of a circular reference, but has eventually been " +
"wrapped. This means that said other beans do not use the final version of the " +
"bean. This is often the result of over-eager type matching - consider using " +
"'getBeanNamesForType' with the 'allowEagerInit' flag turned off, for example.");
}
}
}
}
// Register bean as disposable.
try {
registerDisposableBeanIfNecessary(beanName, bean, mbd); // 销毁时调用destroy-method
}
catch (BeanDefinitionValidationException ex) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex);
}
return exposedObject;
}
2.1 实例化
// AbstraceAutowireCapableBeanFactory.java
/**
* 不同策略创建Bean对象
* - 工厂方法
* - 有参构造方法
* - 无参构造方法
*/
protected BeanWrapper createBeanInstance(String beanName, RootBeanDefinition mbd, @Nullable Object[] args) {
// Make sure bean class is actually resolved at this point.
Class<?> beanClass = resolveBeanClass(mbd, beanName); // BeanDefinition中的Class对象
if (beanClass != null && !Modifier.isPublic(beanClass.getModifiers()) && !mbd.isNonPublicAccessAllowed()) { // Class的访问权限
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Bean class isn't public, and non-public access not allowed: " + beanClass.getName());
}
Supplier<?> instanceSupplier = mbd.getInstanceSupplier();
if (instanceSupplier != null) {
return obtainFromSupplier(instanceSupplier, beanName);
}
if (mbd.getFactoryMethodName() != null) { // 工厂方法创建Bean对象
return this.instantiateUsingFactoryMethod(beanName, mbd, args);
}
// Shortcut when re-creating the same bean...
boolean resolved = false;
boolean autowireNecessary = false;
if (args == null) {
synchronized (mbd.constructorArgumentLock) {
/**
* Class类有多个构造方法
* 调用前根据签名锁定要调用的构造方法或者工厂方法
*/
if (mbd.resolvedConstructorOrFactoryMethod != null) {
resolved = true;
autowireNecessary = mbd.constructorArgumentsResolved;
}
}
}
// 已经解析过 就使用解析好的构造函数进行实例化
if (resolved) {
if (autowireNecessary) {
return this.autowireConstructor(beanName, mbd, null, null); // 构造函数自动注入
}
else {
return instantiateBean(beanName, mbd); // 无参构造方法
}
}
// Candidate constructors for autowiring?
/**
* 选择出合适的构造方法
* - 根据参数解析推断
*/
Constructor<?>[] ctors = determineConstructorsFromBeanPostProcessors(beanClass, beanName);
if (ctors != null || mbd.getResolvedAutowireMode() == AUTOWIRE_CONSTRUCTOR ||
mbd.hasConstructorArgumentValues() || !ObjectUtils.isEmpty(args)) {
return autowireConstructor(beanName, mbd, ctors, args); // 构造函数自动注入
}
// Preferred constructors for default construction?
ctors = mbd.getPreferredConstructors(); // 没有解析出合适的构造方法 看看有没有指定构造方法
if (ctors != null) {
return autowireConstructor(beanName, mbd, ctors, null);
}
// No special handling: simply use no-arg constructor.
return instantiateBean(beanName, mbd); // 默认的构造器无参构造方法
}
2.2 三级缓存
// AbstractAutowireCapableBeanFactory.java
/**
* 将创建Bean的objectFactory缓存到三级缓存中
*/
addSingletonFactory(beanName, () -> getEarlyBeanReference(beanName, mbd, bean));
// DefaultSingletonBeanRegistry.java
protected void addSingletonFactory(String beanName, ObjectFactory<?> singletonFactory) {
Assert.notNull(singletonFactory, "Singleton factory must not be null");
synchronized (this.singletonObjects) {
if (!this.singletonObjects.containsKey(beanName)) {
this.singletonFactories.put(beanName, singletonFactory); // 三级缓存
this.earlySingletonObjects.remove(beanName); // 二级缓存
this.registeredSingletons.add(beanName);
}
}
}
2.3 属性填充
// AbstractAutowireCapableBeanFactory.java
/**
* Bean属性填充
* - 可能依赖其他的Bean
*/
populateBean(beanName, mbd, instanceWrapper);
2.4 初始化
// AbstractAutowireCapableBeanFactory.java
protected Object initializeBean(String beanName, Object bean, @Nullable RootBeanDefinition mbd) {
/**
* Aware接口回调
* - BeanNameAware 回调setBeanName方法
* - BeanClassLoaderAware 回调setBeanClassLoader方法
* - BeanFactoryAware 回调setBeanFactor方法
*/
this.invokeAwareMethods(beanName, bean);
Object wrappedBean = bean; // 已经实例化好的Bean对象
if (mbd == null || !mbd.isSynthetic()) { // 不是Spring合成Bean
/**
* BeanPostProcessor后置处理器回调postProcessBeforeInitialization方法
*/
wrappedBean = this.applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
}
try {
/**
* init方法执行
* - 回调InitializingBean的afterPropertiesSet方法
* - 执行init-method方法
*/
this.invokeInitMethods(beanName, wrappedBean, mbd);
}
catch (Throwable ex) {
throw new BeanCreationException(
(mbd != null ? mbd.getResourceDescription() : null), beanName, ex.getMessage(), ex);
}
if (mbd == null || !mbd.isSynthetic()) { // 不是Spring合成的Bean
/**
* BeanPostProcessor后置处理器回调postProcessAfterInitialization方法
*/
wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
}
return wrappedBean;
}
三 流程图
四 Bean创建过程中循环依赖示意图
两个单例Bean，A和B，A依赖B，B依赖A，先创建A
